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James Webb Telescope

Never mind space expansion, the (observable by telescope) Universe gets bigger every time JWST blinks :cool:.
 
The image released showing the most distance galaxies was made from a 12.5 hour exposure, iirc, whereas similar images from Hubble require approximately 10 day exposures. So, scientists are pretty excited as to what (future) longer exposures on the JWST will show.
 
Mike Helland said:
JWST has found the oldest galaxy we have ever seen in the universe

Discoveries from the James Webb Space Telescope are pouring in, with an analysis of the latest data revealing a galaxy that dates back to just 300 million years after the big bang – the oldest we have ever seen

https://www.newscientist.com/articl...est-galaxy-we-have-ever-seen-in-the-universe/
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It looks just like a boil needing lancing lol, I presume that picture is somehow best guess at true colour.
 
Samson said:
I presume that picture is somehow best guess at true colour.
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Not exactly. First of all, what would "true" color actually mean? The color that the light was when it was emitted (before being red-shifted into the infrared, which human eyes cannot see)? But probably you map longer wavelengths onto the red end of the visible spectrum and shorter wavelengths onto the blue end. So in that sense, the colors would correspond to how our own eyes perceive different wavelengths of visible light.
 
Samson said:
It looks just like a boil needing lancing lol, I presume that picture is somehow best guess at true colour.
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I thought it was a whitehead pimple on God's butt. If they pan around a bit we might see God's Black Hole :D.
 
Puppycow said:
Not exactly. First of all, what would "true" color actually mean? The color that the light was when it was emitted (before being red-shifted into the infrared, which human eyes cannot see)? But probably you map longer wavelengths onto the red end of the visible spectrum and shorter wavelengths onto the blue end. So in that sense, the colors would correspond to how our own eyes perceive different wavelengths of visible light.
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Presumably you could blue shift the entire spectrum into the visible light range, keeping the proportions between the frequencies the same. A computer algorithm could do it, based on the known about of red shift in the source.
 
arthwollipot said:
Presumably you could blue shift the entire spectrum into the visible light range, keeping the proportions between the frequencies the same. A computer algorithm could do it, based on the known about of red shift in the source.
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That makes a lot of sense to me. Just cancel out the red-shift, right? You can probably also work out what visible light waves would be present from the infrared waves and known physics of blackbody radiation. And I know that they use emission lines of elements to calculate how much red shift there is.
 
What I hope they have done here is compile a colour visual as though as close as Andromeda today, but I am a little uncertain.
 
Puppycow said:
That makes a lot of sense to me. Just cancel out the red-shift, right? You can probably also work out what visible light waves would be present from the infrared waves and known physics of blackbody radiation. And I know that they use emission lines of elements to calculate how much red shift there is.
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Yes, that's how it seems to me. Kind of like how noise-cancelling headphones work but not really.
 
arthwollipot said:
Yes, that's how it seems to me. Kind of like how noise-cancelling headphones work but not really.
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Perhaps more like how a bat detector works by shifting the bat's calls down to human-audible frequencies. Though of course here the shift would be raising the frequencies to be closer to what they were when originally emitted.

What I'm not clear about is whether that's really something that Webb can do: is the degree of redshift seen in those very distant galaxies suitable for Webb's sensors to see what was originally visible wavelengths and allow the production of a false colour image close to what was originally true colour?

(And that's aside from whether that would be a scientifically useful thing to do or just a cool trick.)
 
This whole discussion reminds me that I did come across a video just the other day from a guy that did his own image processing on the data. He also shows how to do it, for anyone who is curious. I only watched bits and pieces of it myself, but for anyone who is interested in image processing, colorizing and so on, here is the video:

https://www.youtube.com/watch?v=DVuonz26P0w

He also shows where you can download the raw data, and how to find the data you are looking for. Anyone can do it, but there's a firehose of data so it helps to know how to narrow it down.
 
A "true color" image would expose less detail and probably wouldn't look like what a person would actually see. Ignoring issues of distance, perspective, and brightness, color perception depends on more than just the frequency of the light being observed. Think about that "what color is the dress" meme and other optical illusions.

I am not sure there is much to be gained by trying to produce a true color image. But, it might be an interesting exercise.

Back in the days before such data was easily available on the Internet, I bought a big set of CDROMs of data from the Voyager missions. It included software, with source code, for displaying the image. I had fun playing with and modifying the software. It was fun seeing the images slowly rendering on the screen.
 
Other than the "eye candy" images, my main lay-interests in JWST are evidence that life might exists elsewhere, and evidence that either supports The Big Bang/expanding Universe model or not. I also expect "at the length truth will out", so I don't need to worry about Standard Model bias conspiracies.

I imagine (hope) there will be a deep space image that uses JWST's highest resolution and magnification at the longest exposure to see the full extent of how far it can see and what's there (well, what was there when the light/heat was emitted).
 
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Does this thread about the JWST need a major split? The cosmology discussion probably deserves a thread of its own.
 
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